DIY Hot Wheels Drag Race Timer

[Apachexmd] wanted to do something fun for his three-year-old son’s birthday party. Knowing how cool race cars are, he opted to build his own Hot Wheels drag race timer. He didn’t take the easy way out either. He put both his electronics and 3D printing skills to the test with this project.

The system has two main components. First, there’s the starting gate. The cars all have to leave the gate at the same time for a fair race, so [Apachexmd] needed a way to make this electronically controlled. His solution was to use a servo connected to a hinge. The hinge has four machine screws, one for each car. When the servo is rotated in one direction, the hinge pushes the screws out through holes in the track. This keeps the cars from moving on the downward slope. When the start button is pressed, the screws are pulled back and the cars are free to let gravity take over.

The second component is the finish line. Underneath the track are four laser diodes. These shine upwards through holes drilled into the track. Four phototransistors are mounted up above. These act as sensors to detect when the laser beam is broken by a car. It works similarly to a laser trip wire alarm system. The sensors are aimed downwards and covered in black tape to block out extra light noise.

Also above the track are eight 7-segment displays; two for each car. The system is able to keep track of the order in which the cars cross the finish line. When the race ends, it displays which place each car came in above the corresponding track. The system also keeps track of the winning car’s time in seconds and displays this on the display as well.

The system runs on an Arduino and is built almost exclusively out of custom designed 3D printed components. Since all of the components are designed to fit perfectly, the end result is a very slick race timer. Maybe next [Apachexmd] can add in a radar gun to clock top speed. Check out the video below to see it in action. Continue reading “DIY Hot Wheels Drag Race Timer”

Pandaphone is a DIY Baby Toy

[Tyler] was looking for a gift for his friend’s one year old son. Searching through the shelves in the toy store, [Tyler] realized that most toys for children this age are just boxes of plastic that flash lights and make sound. Something that he should be able to make himself with relative ease. After spending a bit of time in the shop, [Tyler] came up with the Pandaphone.

The enclosure is made from a piece of 2×4 lumber. He cut that piece into three thinner pieces of wood. The top piece has two holes cut out to allow for an ultrasonic sensor to poke out. The middle piece has a cavity carved out using a band saw. This would leave room to store the electronics. The bottom piece acts as a cover to hide the insides.

The circuit uses an ATtiny85. The program watches the ultrasonic PING sensor for a change in distance. It then plays an audio tone out of a small speaker, which changes pitch based on the distance detected. The result is a pitch that is lower when your hand is close to the sensor, but higher when your hand is farther away. The case was painted with the image of a panda on the front, hence the name, “Pandaphone”. Based on the video below, it looks like the recipient is enjoying it! Continue reading “Pandaphone is a DIY Baby Toy”

Chicken-powered Pendulum

Every once in a while we get sent a link that’s so cute that we just have to post it. For instance: this video from [Ludic Science]. It’s a wind-up chicken toy that kicks a pendulum back and forth. No more, no less.

But before you start screaming “NOT A HACK!” in the comments below, think for a second about what’s going on here. The bird has a spring inside, and a toothed wheel that is jammed and released by the movement of the bird’s foot (an escapement mechanism). This makes the whole apparatus very similar to a real pendulum clock.

Heck, the chick toy itself is pretty cool. It’s nose-heavy, so that under normal conditions it would tip forward. But when it’s wound up, tipping forward triggers the escapement and makes it hop, tipping it backward in the process and resetting the trigger. The top-heavy chicken is an inverted pendulum!

And have a look, if you will indulge, at the very nice low-tech way he creates the pivot: a bent piece of wire, run through a short aluminum tube, held in place by a couple of beads. Surely other pivots are lower-friction, but the advantage of using a rod and sleeve like this is that the pendulum motion is constrained to a plane so that it never misses the chicken’s feet.

Our only regret is that he misses (by that much) the obvious reference to a “naked chick” at the end of the video.

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The Lightgame Project: A Multiplayer Arduino Game

lightgame_3Summer is upon us. The Lightgame Project is a multiplayer reaction time based game built around the Arduino. It’s a perfect rainy day project for those restless kids (and adults!). Designed by two undergraduate students [Efstathios] and [Thodoris] for a semester long project, all the hard work has already been done for you.

There are tons of reasons we love games that you can build yourself. For one, it’s an amazing way to get children interested in hobby electronics, making, and hacking. Especially when they can play the game with (and show off to) their friends. Another reason is that it is a perfect way to share your project with friends and family, showcasing what you have been learning. The game is based on your reaction time and whether or not you press your button when another players color is shown. The project is built around two Arduinos connected via I2C. The master handles the mechanics of the game, while the slave handles the TFT LCD and playing music through a buzzer.

I2C is a great communication protocol to be familiar with and this is a great project to give it a try. [Efstathios] and [Thodoris] did a great job writing up their post, plus they included all the code and schematics needed to build your own. It would be great to see more university professors foster open source hardware and software with their students. A special thanks goes out to [Dr. Dasygenis] for submitting his student’s work to us!

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Learning letters, particularly R, F, I, & D

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After [yohanes] picked up a toy at a yard sale – a Leap Frog Letter Factory Phonics – he thought he could do better. The toy originally asked a child to find a letter, and after digging one of 26 plastic characters out of a plastic tub and placing them on the Letter Factory’s sensor, would play a short musical ditty. [yohanes]’ version does the same, but because he made it himself it is infinitely more expandable.

The letters for [yohanes]’ version are RFID tagged. This, combined with a cheap RFID module and a bluetooth module means a Raspberry Pi can read RFID cards from across the room. From there, it’s a simple matter of writing up some Python to ask his toddler for a letter, reading the bits coming from a bluetooth, and keeping score.

The build isn’t over by a long shot. [yohanes] still needs to make his build multilingual by adding Indonesian and Thai. There’s also a possibility of adding a spelling game to make it more interesting.

Tickle-Me-Elmo… Frozen In Carbonite

elmo-in-carboniteWe at [HAD] love any hack that combines children’s toys with science-fiction technology, so seeing a Tickle-Me-Elmo “frozen” in [Carbonite] is a definite win in our book. It’s also a great argument for joining your local Hackerspace, or just getting together with some like-minded friends. This idea came out of an impromptu brain-storming, or “talking about crazy ideas session” at the [Baltimore Node] hackerspace.

Fortunately [Todd] had access to all the tools necessary to make this “crazy idea” a reality. A [Shopbot] was used to cut out the box, and the side panels were 3D printed with help from these files on Thingiverse. For processing, an [ATtiny85] programmed using an Arduino was used to power this project.

There’s no mention of whether [Todd] would be willing to part with his creation, however, we would guess that there would be no bargaining with him. He’s not going to give up his favorite decoration easily.

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Building a pirate cannon for fun and plunder

Our days by the pool are behind us for the year. But playing pirate ship with a 2-year-old does sound like quite a bit of fun. That’s why [The Stone Donkey] built this pirate cannon prop complete with firing sounds.

The simplicity of the design is pretty brilliant. Three segments of PVC and five fittings make for a realistic looking barrel that won’t throw your back out when you pull this one out for playtime. After some cutting and gluing the entire thing was sprayed with matte black paint. The bit of rope wrapped around the barrel is a nice touch. The base was made with some scrap pine, but it’s that little wooden box on top that makes it really special. It is the fuse box, and a tap of the finger gives a burning fuse sound and video followed by an earth-shattering kaboom. [The Stone Donkey] used his old Droid X Android phone and wrote an app for it that puts on the sound and light show. Take a look in the clip after the break.

Continue reading “Building a pirate cannon for fun and plunder”